Enkephalins and endorphins are morphine-like substances which have recently been discovered to be endogenous in various animal species, including mammals and man. Enkephalins and endorphins are peptides and/or polypeptides. Enkephalins are normally present in the brain.
It has heretofore been observed that enkephalins and endorphins have an ability to act as analgesics, to abolish pain, when administered to various animals by certain special routes (e.g. directly into the brain) that pose practical drawbacks to useful administration. These substances have a drawback that they are addicting, and tolerance develops to them. They have an additional drawback of having an effect of very short duration of action, due to their rapid destruction by other substances endogenous to animal species, including mammals and man. These endogenous substances that destroy the action of enkephalins include at least two known enzymes, carboxypeptidase A and leucine aminopeptidase.
D-phenylalanine and DL-phenylalanine are known chemicals listed in the Merck Index.
Use of phenylalanine has been reported from the Faculty of Medicine, Buenos Aires, Argentina in "Therapy of Depression of Phenylalanine", Arzneim Forsch, Vol. 25, NRl (1975), and "Use of D-Phenylalanine In Parkinson's Disease," Arzneim Forsch, Vol. 26, NR4 (1976). In the report on treatment of depression, DL-phenylalanine was administered in quantity of 50 or 100 mg. per day for 15 days, and D-phenylalanine was administered in quantity of 100 mg. per day for 15 days.
A commercial drug, sold under the Trademark "Deprenon", is available for treatment of depression, by oral ingestion of 3-4 capsules per day. Deprenon's specifications state that each capsul contains:
______________________________________ D-phenylalanine 50 mg. Manitol 90 mg. Pervidone 4 mg. Magnesium Stearate 3 mg. ______________________________________